Mobile video refers to a service such as live broadcasting, broadcasting on demand and downloading of various video/audio contents including movies, entertainments, original works, sports, music, which are provided to users via mobile devices and based on a mobile network. The mobile network includes a general packet radio service (GPRS) network, an enhanced data rate for GSM evolution (EDGE) network, a 3rd generation (3G) network, or a wireless fidelity (WiFi) network, etc. With the rapid development of multimedia and computer techniques, video playing and applications have gained a big success on personal computers (PCs). With the coming of the 3G era, mobile videos become increasingly hot and demands for mobile videos show an explosive growth. Desires of users of visiting multimedia resources anytime and anywhere increase with time.
The playing of a video on a mobile device usually involves a video format conversion problem. Most existing mobile videos need to be processed by a format converting system, i.e., the video program is transcoded according to a specific format and code rate. The processed video program is fit for being played on the mobile device. At present, a format converting system includes a video convertor, an audio convertor, a picture format convertor, a document format converter, etc. With the development of the Internet and the mobile network, there are more and more media playing platforms. Thus, the media platforms support more and more media formats. From cellphone, to IPTV, to high definition digital broadcast, different platforms have different requirements on the formats of the contents, such as encoding format, resolution, and frame rate. Therefore, conversion of content encoding format becomes indispensable.
At present, there are three transcoding requirements: 1) conversion requirement between different video formats, e.g., from moving pictures experts group/motion pictures experts group (MPEG)-2 or MPEG-4 to H.264. 2) Content transmitting requirement: it is required to change the bit rate to meet requirements of different network bandwidths or device playing speeds. 3) Definition requirement: it is required to convert a high definition video to a standard definition video or a low definition video, or vice versa. An example is as follows. In order to edit information and upload the information to a website such as YouTube, a video needs to be transmitted from a camera to a PC. During the transmission of the video data, the conversion is performed, e.g., from the camera (audio video interleaved (AVI) format) to the PC (MPEG-2 for editing or MPEG-4 for storage) and then to the website (H.263/H.264/Flash). If a file on the website needs to be played on the PC, the transcoding is performed to the file to play the file by RealPlayer or Windows Media Player software.
There are the following two manners to enable a user to watch a mobile video on a mobile device.
In one manner, the network is searched for a video in a video format can be played on the mobile device. The video is downloaded to the mobile device for play or is played online. If the video is downloaded to the mobile device for play, dedicated downloading software is usually required. After a long time, downloading of the video is finished and then the video can be played. If the video is played online a website needs to prepare a transcoded target video in advance.
In the other manner, a format conversion is performed using a local transcoding system of the client that the user logs in. Dedicated transcoding software is installed in the mobile device. An original file which needs to be transcoded is imported into the transcoding software. The user may configure transcoding parameters related to a target format to be outputted, such as target file name, code rate, split the video or not, etc. Then the transcoding is started. After the transcoding, it is synchronized on the mobile device again. This manner is not fit for playing on the mobile device. The transcoding procedure on the client is very complicated and is time consuming.